Otitis media (ear infection) is a common problem that bears significant health implications. It is the most common cause of deafness in children in the developed world, affecting up to 80% of preschool children at some time. Second only to upper respiratory infections, it is the most common indication for outpatient antibiotic use in children. Further, it is the most common reason for a child to visit the pediatrician. In the United States, the annual cost of medical and surgical treatment of otitis media is estimated at $5 billion.
Otitis media is an inflammatory and infective process affecting the middle ear and mastoid spaces. After an acute infection, there is often the development of persistent fluid within the middle ear space, known as a middle ear effusion (MEE). Persistence of a MEE can result in hearing loss and recurrent otitis media with effusion (OME). OME is defined as the presence of a middle ear effusion for 3 months or more without gross signs of middle ear infection. However, recurrent ear infections often ensue in OME as the presence of effusion creates a fertile environment for bacterial growth.
The middle ear normally produces mucus. However, inflammatory stimuli, such as bacteria, virus, and allergy, may cause excessive production, increased viscosity, or impaired drainage of the mucus. These changes lead to mucus collection within the middle ear, forming a MEE. MEEs may persist for prolonged durations, especially in children, resulting in hearing loss and recurrent ear infections. Adults may also develop OME and persistent MEE, but are less susceptible than children in most part due to improved Eustachian tube function and position. In both adult and pediatric populations, treatment options typically include ear tube placement or close observation for resolution.
With these important clinical implications, accurate interpretation of middle ear contents proves to be an important and essential determination during the ear examination in all patients. The presence of middle ear fluid is commonly assessed by the existing technologies of otoscopy and tympanometry. However, these both have limitations in diagnostic accuracy and are dependent on the practitioner's experience, warranting consideration of alternate technologies. Tympanometry, for example, is a measure of the compliance of the tympanic membrane obtained by altering the air pressure within the ear canal and is not a true measure of the middle ear space. Therefore, the tympanometry probe placed in the external ear canal must achieve a tight seal, which is difficult to obtain in young children.